Submersible motor construction



M y 1935- E. MENDENHALL ET AL SUBMERSIBLE MOTOR CONSTRUCTION Filed April 16, 1934 2 Sheets-Sheet l I/v ws/v rams EARL MENDENHALL A rToR/w: x

May 28, 1935. I E. MENDENHALL El AL 2,002,916

7 SUBMERSIBLE MQTOR CONSTRUCTION Filed April 16, 1934 2 Sheets-Sheet 2 /OO) /0/ /OZ\ I I I .//v l/EN TORJ EARL ME/VDENHALL. (/U/V/UJ 5. WIN ORN 15v Ar TORNE 4 V Patent ed Mai v If I umrao srArEs PATENT OFFIE j Earl Mendenhall, Los Angeleaand Junius B. Van

Horn, Alhambra, Cali.f., assignors to Menhorn, Inc., Los Angeles, osuc, a corporation of California Application April 16,1934, serial No. 720,774 16 (01. 172-36) Our invention relates to submersible structures, junctionwith a pump for maintaining the excess and more particularly to a submersible electric internal pressureqhthe seal. motor. Many oi the features incorporated inthe A further object of the invention lies in the present invention are particularly applicable to provision of anovel control means for controlling 5 submersible structures in which a differential the submersible structure, usually a submersible 5 pressure is maintained on the sealing means motor, in, response to the pressure or quantity which seals the junction of the shaft and the shell. of the internal liquid.

The invention will be particularly describedzwith A further object of the invention is to provide reference to such an unbalanced system, though 'a novel control means including a switch means it will be clear that many 01' the features of th operated by a movable diaphragm means. 10 invention find utility in other systeins. Still another object of the invention is to pro- It is an object of the present invention to provide a novel system for introducing electric vide a shell suchas a motor shell containing an potentials into a shell in which different pressures internal. liquid, and to provide a pumping means are developed in different sections thereof.

in the shell for pumping this internal liquid-in Further objectsand advantages of the inven- 15 such a manner that the pressure on the internal tion will be made evident hereinafter. portion of the seal is somewhat in excess of the Referring to the drawings, pressure on the external portion of the seal so Fig. 1 is a vertical sectional view oi one form that any leakage which takes place will be out of the invention.

ward from the shell rather than inward into the Figs. 2 3, and 4 are sectional views taken on 20 shell. In this way it becomes possible to prevent corresponding lines of Fig. 1. A entrance of any external liquid in which the V Fig. 5 is a vertical sectional view oi an altershell may be submerged, thus making it posnative form of the invention and illustrating one sible to submerge the motor in a liquid which form of electrical connection which may be used would be injurious to the working partsof th in conjunction therewith. g5 motor should it come in contact therewith. Fig. 6 is a horizontal sectionalview taken on It is a further object of the present invention the line 6-4 of Fig. 5.

- to provide a pump for pumping the internal liq- Referring particularly to Fig. 1, we have illusuid through a closed circulation path in cooling trated a submersible motor structure including relationship with the motor. a motor shell indicated in general by the numeral 3 A further object of the invention is to throttle l0, and an electr c m to ind c ed in al by the flow of the internal liquid moving through the numeral II. The upp 'e d 0 e S ell 018 this closed circulation path in such a manner closed by an upper wall l3 which cooperates with t t. t discharge of th pump means i efiective an intermediate wall It in defining a seal chamin increasing the pressure 'on the internal portion ber I5. The intermediate wall l4 cooperates with 35 oi the seal. l a lower wall l6 in defining a motor chamber ii A further object of the invention lies in the pmin which the motor I I is positioned. An intervision of anovel system which compensates for exmediate wall [8 extends across the motor shell pansion of the internal liquid due to heat generl0 and cooperates with the lower wall l6 in de- 40 ated by the motor and which compensates for any fining an intermediate or pumping chamber 20, 40 change in volume effected by'the pumping means. while the intermediate wall l8 cooperates with This system for compensating for expansion 2. lower wall 2| of the motor shell ID in defining may take the form of a chamber adapted'to rean expansion-compensating or pressure-transceive-any excess internal liquid, and it is an object ferring chamber 23.

of the present invention to provide such a struc- Various constructions may be used for forming 45 ture. 'such a motor shell, but in the form shown this Afurther object of the invention lies inthe pro- "shell is formed in three sections 25, 26, and 21. vision of a pump means operatively connected to The intermediate section 25 may be permanently the motor and intaking from such an expansionassociated with a stator 28 of the motor ll, es-

compensating chamber. v pecially if a motor of the can type is utilized, in 50 Another object of the present invention is to which event the intermediate section 26 may comprovide a movable diaphragm means which may prise the sheath around the stator. If such acompensate for expansion, and to provide asystem sectional shell is utilized it is desirable to secure inwhich the internal forcesin such a movable diathe sections 25, 26, and 21 together in fluidtight phragm means may, if desired, be utilized in conrelationship. In the iorm shown this is acccm- 5s plished by at use of a series of bolts so and a:

' respectively associated with the sections 25 and 21 and extending into some portion of the intermediate section 26 to clamp these sections together and-form fluid-tight joints therebetween. In the embodiment illustrated, these bolts are threaded into the sheath of the stator 28. If desired gaskets 33 may be positioned between the adjacent sections. So also, if desired, the upper andlower walls I3 and 2! may be detachably connected to the upper and lower sections 25 and 27 respectively to facilitate adjustment of the bolts 30 and 3|. 7

The motor II also includes a rotor 35 spaced from the stator 28 in the usual manner to define a gap .36 which may serve as a. circulating passage,

in a manner to be hereinafter described. This rotor 35 is operatively connected to ashaft 37 journalling bearings 38 and 39 respectively retained in the walls It and It. In the embodiment shown the upper end, oi? this shaft 31 extends through the seal chamber 15 and through a sealing means ll! which seals the junction of the shaft and the motor shell "I, this shaft then extendingupward to any suitable driven mechanism such as a pump, not shown.

Various types of sealing means may be utilized,

-,and-if' a pressure difierential is maintained on this sealing means, it is not necessary'that the sealing'means be of such type as to absolutely prevent any passage of liquid therethrough. In-

stead, this sealing means may be of such a type as topermit the passage of minute amounts of liquid therethrough, the diflerential pressure on the sealing means being relied upon to insure that any leakage will be outward from the shell rather than inward into the shell. Such a sealing means provides an internal portion communicating with the internal liquid inside the motor shell Ill and provides an external portion communicating with whatever medium is outside the shell, this medium usually being the external liquid in which the motor is submerged. One type of such. seal is illustrated in Fig. 1 as including a gland l2 compressing a packing material 43 positioned Q applicable to structures which are to be sub-'- merged in water, form this case the liquid below the level A-A can be the water in which the motor is submerged. In this instance it'is desirable to provide an open communication between the lower end of the chamber 23 and the external liquid, this being provided in the embodiment.

7 shown by a pipe 45 extending upward-along the motor shell and terminating at a position near the upper end of this shell so as to be in open communication with the external liquid. at this point. Such a construction permits the motor shell to be preliminarily filled with the internalliquid when the motor is, being lowered into its submerged position without danger of escape of internalliquid. If desired, both the.internal and external liquids may be preliminarily positioned in the motor shell before submergence. As the motor is lowered beneath the surface of the external liquid, the pressure in the chamber chamber 23.

51, the gap 36 and the openings 53.

23 will, of course, increase due to the open communication between this chamber and the external liquid. A corresponding pressure is built up on the internal liquid in the upper part of the motor shell so that prior to the time that the motor is energized, the pressures inside and outside the motor shell are substantially equal. Exact equalization is sometimes undesirable, and in reality is never obtained with the system showh in Fig. 1, for the liquids are in pressure-equalizing Greatest tendency'toward intermixture of the internal and external liquids occurs in the seal when the shaft 31 is rotating. There is little tendency toward such intermixture when the shaft is stationary, butmovementof this shaft tends to effect considerable intermixture at the sealing surfaces. It is thus desirablethat the differential pressure be built up on the seal when the motor is energized. .This may be accomplished by the use of a pumping means indicated by the numeral '50 and operatively connected to the shaft a1. In the form shown this pumpin means takes the form of an impeller 5| positioned on the lower end of the shaft 31, the eye of the impeller extending into an opening 52 of the inchamber 23and delivers this liquid under pressure tothe intermediate chamber 2,0.- .A passage 5| is provided to transmit this pressure to the seal chamber I5, this passage being formed through the sections 25, 23, and 21, as shown.

We prefer to utilize the pumpingmeans 5010:- another purpose; namely, circulating the internal liquid in cooling relationship with the motor H. The passage 54 extends'in cooling relationship with the motor and conducts the lntemal liquid from one-end .of the motor to the other. It is preferable-to provide a return passage for returning this internal liquid to the intake of the pumping means 50. Such a return passage may be in the form of any passage communicating between the seal chamber i3 and the. intake of the'pump means 50, such a passage preferably extending in cooling relationship with the motor. In the embodiment shown this return e may include the gap, 36, the liquid being conducted tothe upper end of this gap through a plurality of openings 51 in the upper wall II. The

internal liquid is conducted from the vicinity of the lower end of the gap 36 through openings 33 formed through the lower section 21, these openings communicating with the upper end of the thus be considered as including the penings tation of the impeller 5| thus sets up a closed circulation of internal liquid flowing through a closed circulation path indicated by the arrows. A portion of this path lies in the zone immediately inside the motor shell it so that if theinotor shell is submerged in a cool external liquid, t e heat developed by'the motor is first conducted to the internal liquid flowing in the closedcirculation path,.and is then conducted through the walls.

of the motor shell to the external liquid. This type of cooling has been found to be very advantageous. It is sometimes desirable to interpose a baflie 59 in the chamber 23 above the sur (5 The return passage means mayface of contact A-A, this baille providing one or more pressure-transferring openings but isolating thecirculating internal liquid from the surface of contact A-'.-A, thus allowing quiescent contact between the bodies of internal and external liquids. However, this baille can be dispensed with in some instances.

If such a closed circulation of the internal liquid is utilized, it is preferable to interpose a throttle means in the closed circulation path in such position that a back pressure is built up which maintains the exces pressure on the internal portion of the seal 48. Such a throttle means can be any restricted passage interposed in the closed cinpulation path, preferably in the return passage. In theform illustrated the gap 88 may be utilized in this capacity, if the cross-sectional area of this gaplsmade small. Thus, the passages may be made relatively large so that the pressure drop therein is small, the pressure in the seal chamber I! being substantially the same as the'dlscharge pressure of the impeller ii. The internal liquid flowing through the closed circulation path is throttled by the gap 38 so that the pressure in the passage 88 is substantially the same as the intake pressure of the impeller I. It will be clear, however, that a throttle means other than the gap 38 may be utilized, it being often possible to decrease the size of the openings 81 or 88 tofunction in this regard.

Current is supplied to the motor I I through an armored cable or pipe 8| carrying conductors which are electrically connected to the motor. As shown these conductors extend into the chamber 13 and upward through an opening" into the motor chamber ll. One of the conductors, usually not connected to the motor ll, is indicated by the numeral 82 and is electrically connected to an electrode 63 insulated from the motor shell and extending downward in the chamber 28 through an opening in the basic 8! if this bailie is used. Should the internal liquid contract to a sufllcient degree, or should sumcient internal liquid escape through the seal ll, the level A-A will rise so that the external liquid in the chamber 23 will contact the live electrode 88, thus completing a control or indicating circuit such as will be described with reference to the form of the invention shown in Fig. 5. Additional internal liquid can be supplied to the motor shell II at this time to again lower the level A-A. In the embodiment'shown this additional internal liquid can be supplied to the motor shell through a pipe 85 in which the conductors extend upward, this pipe extending to a point above the external liquid in which the motor shell is submerged.

Referring particularly to Fig. 5, the structure therein shown is quite similar to the structure shown in Fig. l, the motor shell being reversed in position so that the shaft extends downward so as to be operativeiy connected to a driven means such as a pump positioned below the motor structure. The seal chamber It is thus at the lower end of the motor structure, while the pressure-transferring or expansion compensating chamber 28 is positioned at the upper end thereof. No pipe 45 is used in this form of the invention. Instead, an opening I! is .formed in the wall 28.

In this form of the invention expansion of the internal liquid and pressure transfer between the internal and external liquids is effected by the use of a movable diaphragm means 18 which in effect closes one portion of the motor shell. Preferably this movable diaphragm means is in the form of a collapsible bellows defining. a chamber 11 which is in communication with the external liquid through the opening 15. If'such a collapsible bellows is utilized, it is desirable to position it in the chamber 23. Thus, in this form of the invention the internal and external liquids are separated by the movable diaphragm means 16, and expansion and contraction of the internal liquid is compensated for by movement of this diaphragm means ",it being understood I that this diaphragm means will move in response to pressure'changes of the internal liquid and in response to the quantity of internal liquid in the motor shell. Thus, as the internal liquid gradually leaks through the seal 48, the diaphragm means will expand inward.

If desired, this diaphragm means may be so constructed that the internal stresses therein assist in maintaining a pressure diiIerential on the seal. Thus, if this diaphragm means is formed so that its normal position would be more expanded than shown in Fig. 5, the contraction of this diaphragm means to the position shown in Fig. 5 would set up internal stresses which would assist the action of the pumping means 50 in establishing the desired pressure diilferential on the seal 48. So also, this form of the invention utilizing the 'intemal stresses in the diaphragm means 16 can be made to maintain a slight pressure difierential on the seal 40 even when the motor is not energized. The action of the internal stresses in the diaphragm means '18 can, of course, be augmented by externally applied resilient forces such as that which might be exerted by a compression spring between the wall II and the movable end of the diaphragm means 18, or by a suitable weight applied to this movable end. Regardless of the presence of assisting internal forces, it will be clear that the diaphragm means.

16 serves in the additional capacityof transmitting to the internal liquid pressure variations in the external liquid so that the desired small diflerential pressure can be maintained by the pumping means 58.

. In this form of the invention current is supplied to the motor through an upward extenhing cable 88 shown as enclosing four conductors, three of which are respectively indicated by the numerals 8|, 82, and 83, these conductors being electrically connected to the motor. The fourth conductor indicated by the numeral 84 is electrically connected through a flexible lead 85 to a contact 86, this contact being insulated from the diaphragm means I6, but operatively connected thereto by an insulating block 81. A corresponding contact 88 is mounted on the wall l8 in a position to be engagedby the contact 86 when the diaphragm means I8 reaches a predetermined lower position, the contacts 86 and 88 forming a switch means.

i The conductor 84 forms a part of a control circuit electrically connected to a suitable control "or indicating means capable of indicating or directly controlling the submersible electric motor. There are various ways in which this control may be efiected. Usually the switch means valve 88 controlling the flow of internal liquid zone to reduce the pressure therein. Thls-isf aodaom from a tank 8! to thechamber 23 through a pipe often desirable inasmuch "as a lower pressure 82. /Preferably a check valve 83 is provided so difierential is maintained at the junction of the that no return flow. can take place in the pipe cable-enclosed orpipe-enclosed conductors and 82, though this check valve is not always essential the shell than would be the case it the conductors and can often be dispensed with. extended into a higher-pressure zone of the Also connected to the conductor 84 through a structure. switch 84 is a hell or other indicating means 85 While many of the features have been shown .which, when actuated, indicates to the operator associated with the motor structure in which a that the control circuit is closed and that the difierential pressure is maintained on opposite submersible motoris in need of attention. The sides of the seal, this combination is not essenconductor 84 is also connected by a switch 85a tial to the novelty of many of these features.

to a solenoid 88 which, when energized, opens Thus, the idea of providing a pumping means the contacts of a switch 91 connectedin series for circulating internal liquid from one end of with a holding coil 88 of a main switch 88 0011- the motor to the other ina closed path may-be trolling the 'energization of the motor. Thus, used regardless of the function of this pumping energization of the solenoid 88.will break the means in setting up a differential pressure in holding circuit of the switch 88 and thus allow the seal. So also the sectional shell constructhis switch to quickly open to de-energize the tion finds utility regardless of its association with motor, this switch connecting the conductors8i, an unbalanced system. The provision of means 82," and 83 to conductors I80, IM, and I82 oija for compensating for expansion may alsobeused 1 supply line. The conductor I82 is grounded, so in other systems, though this means cooperates that when the contact 88 engages the contact with the pumping means in a particularly de- 88 the circuit is completed from the conductor sirable way if an unbalanced system is utilized. I82 through ground and through the external Inother instances, howeventhis expansion-comliquid to the motor shell i8 and thence to the pensating means can be used independently 01' a contact 88, the currentthen flowing through the pumping means to compensate for the inevitable contact 88, to the conductors 85 rent returning to the conductor solenoids 88 or 88 o'r the indicating IM through the when the motoris energized in a manner to heat means 85;. this liquid. In the absence of 'such expansion- The control circuit will remain closed only while compensating means the expanding liquid would the contacts 88 and 88 are in engagement. As *set up detrimentally high-pressure difierentials additional internal liquid is delivered to the pipe, on the seal and. when contraction took place,

82, this circuit. is thus broken. Due to the time would allow external liquid to enter theinterior lag between the opening 01'. the valve 88 and the of the motor shell. I

' illustrated finds delivery of internal liquid to the motor shell, sep- So also, the control means and 84, the curexpansibn cf the internal liquid which'takesplace' aration of the contacts 88 and 88 will immediately utility regardless of whether or not it is combined close the valve 88 but flow of the internal liquid with an unbalanced system.

already delivered to the pipe 82 to the chamber Various changes and ifi i ns may be 23 will not be prevented until equilibrium conmade without departing from the spirit oi the ditions are reached. Thus, if the pipe 82 is open invention and it will. be understood that the "to the atmosphere at its upper end, the level of e dim s herein set forth in detail have been vmerged. The'lpipe 88 is usually relatively long,

the internal liquid therein under equilibrium conselected for illustrative P p nly and not ditions will be somewhat above the surface of as l m 1 inventive pt to the details the external liquid in which the motor is subof the particular embodiments herein disclosed."

Our 'copending application Serial No. 634,808, and of small-diameter. so that an appreciable fil september 1932, 15121 and claims time elapses between the instant that the valve various systems'ior-maintaining a pressure dil- 88 is openedand the'instant when the adgtionally ierential on opposite sides-o! a seal, the'present suppliedliquid reaches the surface ofth internal application being directedto' an improvement liquid in the pipe 82. This action is very desirover the structures shown in this copending anable for the diaphragm means 18 continues to plication. So also, our copending application be deformed in a direction to separate the conserial No. 524,494, filed March -23, 1931.- contains tacts88 and 88 even aiterthe valve is closed claims on a control system ,for an electric'motor. and until pressure equilibrium conditions be- We claim as our invention: tween the pipe 82 and the chamber 23 exist. A 1. In combination in a submersible electric reserve supply oi internal liquid is thus delivered motor: a motor shell containing an internal liquid to themotor shell with each closing of the conand adapted to be submerged in 'anexteinal liqt r it, uid; an electric motor in said motor shell and It may often'be desired to render inoperative providing a shaft extending through said shell; one or the other of the control means shown asa seal at the junctionyof said shaft and said sociated with'this control circuit. Thus; ii the shell and providing an internal portion contacted operator desires that the disconnect means by' said intemsl'liquid-and an external portion formed by the solenoid means 86 be rendered incommunicating with said external liquid; pumpoperative, he can open the switch 8841, allowing ing means in that end 01' said she opposite said the switches 84, a to remain closed. Similar seal and intaking internal liquid from one secly, if it is desired to disconnect the indicating tion of said shell and dischar in said internal means from the circuit, the switch 84 may be liquid at higher pressure into another section or opened. 80 also, i! the disconnect means is not to be used-the switch 88a. can be opened to accomplish this result.

In both forms of the invention illustrated the conductors extend through the shell and into a low-pressure zone, the intake "of'the corresponding pumping means 58 communicating with this said shell; and means transferring the discharge pressure or said pump to said internal liquid contacting saidinternal portion oi said seal to maintain on said internal portion of said seal a pres-- sure in excess or the pressure on said external portion of said seal.

3, In combination a submersible electric from one section of said shell and discharging said internal liquid at higher pressure into another section of said shell to establish a closed circulation of said internal liquid in said shell and moving through a closed circulation path, a portion of said path communicating with said internal portion of said seal, there being a return flow of said circulated internal liquid to said one section of said shell from said other section of said shell; and throttle means for throttling said return flow taking place from the vicinity of said seal and communicating with said internal portion of said seal to build up a back pressure on said closed circulation and which back pressureis transmitted to said internal portion of said seal to build up thereon a pressure, said throttle means being spaced from said pumping means.

3. In combination in a submersible electric motor: a motor shell containing an internal liquid and adapted to be submerged in an external liquid; an electric motor in said motor shell and providing a shaft extending through said shell; walls defining a seal chamber communicating with the junction of said shaft and said shell; walls defining an intake passage and a smaller discharge passage communicating with said seal chamber; pump means associated with said shaft and intaking internal liquid from a portion of said shell spaced from said seal chamber, the discharge of said pump means communicating with said intake passage and the intake of said pump'means communicating with said discharge passage whereby said pump means circulates neutral liquid into and from said seal chamber, said discharge passage throttling said flow to build up a pressure in said seal chamber; and a seal for sealing said junction of said shaft I and said shell and providing an inner portion communicating with said seal chamber.

4. In combination in a submersible electric motor: a motor shell containing an internal liquid and adapted to be submerged in an external liquid; an electric motor in said motor shell and providing a shaft extending through said shell; a seal at the junction of said shaft and said shell and providing an internal portion communicating with said internal liquid and an external portion communicating with said external liquid; pumping means intaking internal liquid from one section of said shell and discharging said internal liquid at higher pressureinto another section of said shell; means transferring the discharge pressure of said pump to said internal portion of said seal to maintain on said internal portion of said seal a pressure in excess'of the pressure on said exte portion of said seal; and means for transferring pressure between the intake of said pump means and said external liquid.

5. In combination in a submersible electric motor: a motor shell containing an internal liquid and adapted to be submerged in an external liquid; an electric motor in said motor shell and providing a shaft extending through said shell; a sealat the Junction of said shaft and said shell and providing an internal portion 7 5 communicating with said intemai liquid and '5 an external portion communicating with said external liquid; pumping means intaking internal liquidifrom one section of said shell and discharging said internal liquid at higher pressure into another section of said shell to establish a closed circulation of said internal liquid in said shell and moving through a closed circulation path a portion of said path communicating with said internal portion of said seal; throttle means in said closed circulation path and communicating with said internal portion of said seal to build up a back pressure on said closed circulation and which back pressure is transmitted to said internal portion of said seal to build up thereon a pressure; and means for transferring pressure between the intake of said pump means and said external liquid. 7

6. In combination in a submersible electric motor: a motor shell containing an internal liquid and adapted to be submerged in an external liquid; an electric motorin said motor shell and providing a shaft extending through said shell;-

walls defining a seal chamber communicating with the junction of said shaft and said shell; walls defining anintake passage and a smaller discharge passage communicating with said seal chamber; pump means associated with said shaft and intaking internal liquid from a portion of said shell spaced from said seal chamber, the discharge of said pump means communicating with said intake passage and the intake of said pump means communicating with said discharge passage whereby said pump means circulates neutral liquid into and from said seal chamber, said discharge passage throttling said flow to build up a pressure in said seal chamber; a seal for sealing said junction of said shaft and said shell and providing an inner portion communicating with said seal chamber; and means for transferring pressure between the intake of said pump means and said external liquid.

7. A combination as defined in claim 2 in which said closed circulation path includes passage means in cooling relationship with said motor and includes zones immediately inside said shell and into which zones said pump directly discharges whereby said internal liquid flows through said closed circulation path in cooling relation with said motor and in heating relation with said shell to transfer heat from said motor to said external liquid through said shell.

8. In combination in a submersible motor structure: a shell containing an internal liquid and submerged in an external liquid; a motor,

in said shell and providing a; shaft extending therefrom; pressure-transfer 'means for transferring pressure between said internal liquid and said external liquid; a pumping means in said shell at one end of said motor, the intake of said pumping means communicating with said pressure-transfer means; walls forming cooling passages extending through said motor and respectively communicating at one end with the discharge and intake of said pumping means, the other ends of said passages being in communication with each other whereby said pumping means sets up a closed circulation of internal liquid through a closed circulation path transversing said motor and including saidcooling passages; and a seal at the junction of said shaft and said shell and providing an internal portion communicating with said internal liquid flowing through said closed circulation path whereby the pressure on said internal portion is controlled by said pumping means.

g 9. In" combinationin a submersible electric motor: a shell defining a chamber substantially filled with an internal liquid said shell being submerged in an external liquid; a motor in said atshaft associated with said motor and from; said shell; sealing means at the junction of said shaft and said shell and including'an internal portion communicating with said,

internal liquid and an external portion communicating with said external liquid; pump means in said shell and pumping-said internalliquid, the

discharge of said pump means communicating with said internal portion of said seal to build up thereon a pressure greater than the pressure 01isaid external portion of said seal; walls defining passage means extending from one end of said motor to the other in cooling relationshipwit saidv motor, said pump circulating said internal liquid through said passage means in .a closed circulation path; and means for compensating for the expansion of said internal liquid when heated by the operation of said motor, said mans including walls defining a chamber comunicating with saidinternal liquid and receiving the excess of said internal liquid caused by the expansion thereof.

10. Incombination: a submersible motor striicture including a motor shell and a motor therein; movable diaphragm means associated with said shell and movable in response to changes in pressure in said shell; switch means operatively associated with saidmovable-diaphragm means to close when saidmovable diaphragm means v reaches a predetermined position; control means for said submersible motor structure; and a circuit connecting said control means and said switch-means whereby said control means is actuated in response to the position of said movable which said motor shell includes an internal liquid diaphragm means. a

11. A combination as defined in claim 10 in and in which said movable diaphragm means separates said internal liquid from the medium pressure therebetween.

12. In comb tion in a submersible motor structure: a otor shell containing an internal liquid and'submerged in an external liquid; walls defining-a seal chamber at one end of said motor shell and containing internal liquid; a seal for sealing said external liquid from said internal liquid in said sealing chamber; walls defining a motor chamber in said shell; a motor in said motor chamber and heating said internal liquid to cause ,7 expansion thereof; means for compensating for "said expansion; walls forming an intermediate chamber in said shell; walls forming cooling passages extending from one end of said motor to the other end thereof in cooling relationship.

therewith, .at least one of said passages communicating between said seal chamber and said intermediate chamber, at =least one of said passages communicating between said seal chamber and said means for compensating for said expansion of said internal liquid; and pump means circulating said intemal'l iquid through said passages in a closed circulation path; said pump around said motor shell in a manner to transfer a motor in said shell; me

the pressure in one zone of dsshell to a pres-- means being operatively. associated with said motor.

13. In combination in a submersible motor structure: a motor shell defining a motor chamher, an intermediate chamber and an expansion-- compensating chamber; a motorv in said motor chamben a shaft associated witli'said motor; pump means operatively connected to said shaft and intaking from said expansion-compensating chamber and discharging into said intermediate chamber; and passage means extending in cooling relationship with said motor and connecting said intermediate chamber and said expansion--.

lli

compensating chamber, said pump means circu I lating a cooling medium from said expansioncompensating chamber into said intermediate:

vchamber and through said passage means in a closed circulation path". a

14. In combination ii -a submersible electric.

motor: a shell 'containing'an internal liquid and submerged in an exte'rnal'liquid; a motor in said shell; a shaft associated with said motor and extending from said shell; a seal at the junction of said shaft and said shell and providing an internal portion communicating with said internal liquid and an external portion communicating eration and whensaid shaft moves relative tosaid seal. a

15. A combination as defined inclaim '14 in which said last named means includes a pump operatively connected to said shaft; the discharge pressure of said pump raising thepressure on said internal portion of said seal when-said pump is operating. r. i

16. In a submersible electric motor, the combination of; a-motor shell submerged in an external liquid andl'containing an-internal liquid; '-=for'building up sure above that in another zone of said shell and above the pressure of said external liquid at the depthv of submergenceof said finotor' shell; and meansfor conducting an electric current into said shell and to said electric motor, said means extending through thewalls of said shell into the lower-pressure zone thereof whereby any pressure diiferential at'='the junction of said shell and said means due to a pressure diiference between said internal and'external liqulds at said junction will be lower than the pressure differential which would exist if said means extended through said shell into the higher-pressure zone thereof. I

' EARL MENDENHAIL. I JUNIUS B. VAN HORN. 

